2 2 PSYCHE [February 



sense of sight then, guests of the mimicn^ type have probably been developed 

 through a natural selection exercised by the ants of the nest in which they live. 

 This selection tends to produce a convergence of the guests toward the form of 

 their hosts. 



In the case of certain blind ants, however, for example members of the genus 

 Ecitofi, the cause for a mimicry of color (and perhaps also form) cannot depend upon 

 the ants themselves, for they cannot see. Recently Wasmann ^ has taken a very 

 peculiar view of this question. In regard to my suggestion (Amer. Nat. XXXVl, 

 367 (1902)) that the resemblance in color and form of Ecitonidia wheekri Wasm. to 

 Ecitoti schmitti Em. is due to the influence of outside enemies, he thinks that this is 

 untenable. His chief objection with regard to color seems to be that the species of 

 Eciton which have no external eyes have no known guests which mimic them in 

 color, while those with rudimentary eyes, e. g. Eciton schmitti Em., have. He is 

 evidently unaware of the fact noted by Wheeler^ that the external eyes of Eciton 

 schmitti are mere vestiges which have no connection with the brain, and are hence 

 of absolutely no use ! This, then, places E. schjtiitti on the same basis as the other 

 species of Eciton. and we cannot say that they exercise any selection over their 

 guests as regards color. The fact still remains that some ecitophiles are similar to 

 the host ant in color while others are not.^ However, with regard to the species 

 of Ecitonidia which I have observed alive with its host ant {Eciton schmitti Em.), 

 I am firmly convinced that its color resemblance is wholly for protection against 

 insectivorous animals. No one can observe the files of this ant marching for long 

 distances in the open glare of the Texas sun without being satisfied that color 

 resemblance to its unpalatable host is very necessary to protect it from insectivorous 

 enemies. On the other hand when one sees thousands of these same ants huddled 

 together in a writhing mass in some small cavity under a stone, in company with 

 specimens of Ecitonidia, it is hard to believe that the guests' presence is unknown 

 to the ants, or that they could not get rid of them if they attempted to do so. 



In spite of their blindness, it is probable therefore that Ecitons with such 

 habits cannot as readily be deceived by a mimic as seeing ants which do not swarm 

 in this manner. 



iZool. Anz. Bd. XXVI, No. 704, p. 581. 

 2 Biological Bulletin, III., p. 188. (1902.) 



^ Possibly after the habits of some of the tropical species of Eciton are more carefully studied, reasons for the color 

 difference may become apparent. 



